A helium-neon laser emits red light having a wavelength of 632.8 nm and a power of 1.85 mW.How many photons are emitted each second? (h = 6.63 × 10−³⁴ J⋅s,c = 3.00 × 10⁸ m/s,and 1 nm = 10−⁹ m) A)5.9E+15 B)3.7E+34 C)5.9E+24 D)5.9E+18 E)1.2E+17

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Quizplus · Accepted Answer

To find the number of photons emitted per second, we first convert the wavelength to meters: 632.8 nm = 632.8 × 10^-9 m. The energy of a single photon is given by E = hc/λ, where h is Planck's constant (6.63 × 10^-34 J⋅s), c is the speed of light (3.00 × 10^8 m/s), and λ is the wavelength in meters. Substituting the given values, we get E = (6.63 × 10^-34 J⋅s)(3.00 × 10^8 m/s) / (632.8 × 10^-9 m) = 3.14 × 10^-19 J per photon. The power of the laser is 1.85 mW, which is 1.85 × 10^-3 J/s. The number of photons emitted per second is the total energy per second divided by the energy per photon: (1.85 × 10^-3 J/s) / (3.14 × 10^-19 J) = 5.9 × 10^15 photons per second.

A Helium-Neon Laser Emits Red Light Having a Wavelength of 632.8